Transmission system



ept 13 9 F. H. KROGER 3 TRANSMISSION SYSTEM Filed March 19 1950 QHHMHHMHU T i N i JNVENTQR FRED a. an

ATTORNEY primar Patented Sept 1-3, 1932 UNITED T E-'5 PATENT OFFICE rn-En HQKROGER, or

nrnenwoon, NEW JERSEY AssieNon T RADIO conroim'rron OF AMERICA, A CORPORATION or DELAWARE V I TRANSMISSIOIl' SYSTEM "Application filed. 'Mfarch 19, 1930. Serial No 437QOO 5.

This invention relates to radio apparatus and in particular to radio transmitters including oscillation generators and radiating systems. i V

More in detail this invention relates to transmission lines, and to a novel method of and apparatus forfconnecting the output or tank circuit of an oscillation generator or amplifier through a transmission line to the cir-- cuit to be energized thereby.

In radio transmiss on apparatus known heretofore the transmisslonhne 1s termmated at the output of the oscillation generator in a secondary winding of a transformer the y winding of whichis connected in some manner to the anode cathode circuit of the oscillation generator or to the amplifier stage fed by thegeneratonwhile the remote end of the transmission line terminates in the primary Winding of a transformer the secondaryof which is'connected insome-manher in the load circuit.

Use of the apparatus known attended with numerous disadvantages a few of which will be listed here;

When transformers are utilized to connect the ends of the transmission line to the oscil lation generator output and to the antenna radiating system considerable capacity is present between the windings of the transformers due to the size of the windings and the close spacing thereof. ThlS' lnherent capaclty 1s undesirable in all cases and especially undesirable where the apparatus is to be used to generate, transmit and utilize oscillations at the high frequencies necessary in short wave work.-

Another disadvantageinherently present in apparatus of theabove nature-due in part from the inherent capacity between the wind-' ings and in part from the size of the windmgs and the apparatus 1s that the lmes and apparatus is unbalanced with respect to ground. The latter defect results in losses in energyto ground thus directly reducing the efficiency of the transmission apparatus.

Another objection to the use of transmission lines terminating in transformers as de-.

scribed above results from the fact that'the transformers are more or less of permanent.

heretofore is cuit of the oscillation generator or' final am-,

plifier stage. The transmission line is tapped to appropriate points on this oscillation circuit in such a manner that when the frequency is "changed there are no dead ends-to the 'winding. The transmission line terminates 1n a second auto-transformer connected in a novel manner to the load circuit. 7 1

In one modification preferably toi'be used when a single'tube is utilized in the final stage of the oscillation generator or ampli-' fier fed thereby the I coupling between the tank circuit and transmission line includes an auto-transformer winding tuned by a capacity and connected on the one hand through a con-denser to the anode of the thermionic oscillation "generator oramplifier and on the other hand through a tapped point to the filament of the thermionic tube. The transmission line is tapped to this inductance on the one hand and on the'other hand to an inductance forming a portion ofthe aerial circuit in such a manner as to balance the line with respect to groundand with respect to the apparatus at each end and to cause all of the antenna current to flow through the coupling inductanceat both ends of the trans mission line. V I

A second modification is to be used preferably with transmitters the final stage of which includes a pair of thermionic tubes in push-pull relation. This modification except for the fact that push-pull arrangement is used is similar in many respects to the modification briefly described above and especially as to the manner in which the transmission line is coupledto the output of the final stage but differs in that at the remote end of the transmission line a condenser is connected in series with the inductance in reactance presentin an arrangement similar to the first discussed modification.

Other objects of the invention and further advantages to be obtained by the use of the )resent novel method and arran ement of connecting the transmitter to a load circuit will be come apparent from the following detailed description and therefrom when read in connection with the drawing throughout which like reference numerals indicate like parts and in which,

Figure 1 shows our novel method of connecting the transmission line between a thermionic generator having a single tube in the output circuit thereof and a load circuit;

while,

Figure 2 shows the method of connecting the transmission line between a thermionic generator having a pair of tubes in push-pull relation and the load circuit.

Referring to the drawing, Figure 1 shows a thermionic oscillation generator or amplifier 1 having an anode 2 connected through a condenser 3 to a tank circuit 4 including an inductance 5 and parallel tuning condenser 6. The anode cathode alternating current circuit is completed through an adjustable tap 7 to the cathode 8 and of generator 1. Direct current potential. is applied to the anode through a choke coil 10 from a source 11 having its negative terminal connected to the cathode 8. A circuit not shown is connected at 12 between the control grid and cathode of generator 1. This circuit may be an input cir.

cuit associated with a source of varying potential or may be an oscillatory circuit coupled' to the anode cathode circuit in a manner to insure oscillation of the apparatus including the tube 1. Heating current for the oathode 8 is supplied from a source not shown.

The transmission line 13 includes a pair of lines tapped at 14 and 15 to points on the inductance 5. The transmission lines 14 and 15 are at the remote terminal tapped at 16 and 17 to an inductance 18 in the load circuit which for purposes of illustration hasbeen shown as an aerial system. A second inductance 19 is connected on the one hand through a tap 20 to the aerial and on the other hand to ground G.

In operation when it is desired to change the wave length of the signals generated and transmitted all that is necessary is totune the tank circuit 4 to the desired frequency and then adjustthe taps 14 and 15 along the inductance 5 to pick off the most effective voltage to be transmitted by line 13 to the aerial inductance 18. The taps 16 and 17 are now moved along the aerial inductance 14 to include that amount of inductance which gives the most desirable results. The aerial may be further tuned by varying the tap 20 on the inductance 19.

By causing the current in the tank circuit 4 to flow through all of the inductance across which the transmission line is connected the transmitter output circuit and apparatus will be balanced with respect to ground as will be the transmission line connected to the output circuit.

The arrangement at the aerial end of the transmission line is such that the transmission line'is completely balanced with respect to ground and at the same time the full transferred from the line to the aerial without varying the tune of the aerial circuit.

In the modification shown in Figure 2 the method of connection at the transmitter end is similar to that shown in Figure 1 except that in Figure 2 the final stage of the oscillation generator includes a pair of thermionic tubes 1 and 1 having their anodes 2 and 2 connected through a tank circuit 4:. The variable tap 7 is connected between a point on the inductance 5 of the tank circuit and ground as in Figure 1. The transmission line 13 is tapped to the desired points on the inductance 5 at the output end and to the desired points on the inductance 18 at the antenna end of the transmission line.

In operation this modification is somewhat similar to the modification shown in Figure 1. However, in this modification the push-pull amplifier is in itself balanced with respect to ground while the transmission line tapped to the inductance 5 is balanced with respect to ground due to the fact that as in Figure 1 all of the current flowing in the transmission line flows in the inductance 5 in the output of the push-pull stage. This modification, however, difi'ers from the modification shown in Figure 1 in that at the aerial circuit end of the transmission line a condenser 21 is connected in series with the inductance 18. This condenser causes the current to flow through all of the inductance tapped by the transmission line thereby eliminating any reactance which would be present in an arrangement as shown in Figure 1.

In both modifications at the load end of the transmission line I have provided two current paths in such a manner that the current path included in the transmission line and the transmission line can be made sym metrical and therefore the transmission line 3 with respect to ground is likewise symmetrical, and the line is balanced with respect to ground.

In both modifications as Will be readily seen by inspection of the drawing, the power fed from the transmission line to the aerial radiating system can be varied without upsetting the antenna circuit adjustments only slight retuning being required. This characteristic also results directly in a further advantage in that the frequency transmitted may be readily shifted through a frequency range without changing the coupling inductances at either end of the transmission line and without unbalancing the transmission line or resulting in losses therein. Both modifications likewise obviate the necessity of transformers and the disadvantages resultant from the use thereof at both ends of the transmission line.

I claim:

1. A thermionic transmitter including a thermionic amplifier having a tank circuit including a tuned inductance connected through a condenser to the anode and through a point tapped on said inductance to the cathode, an aerial circuit including a pair of parallel inductances one of which is variably connected between the aerial capacity and ground and a transmission line tapped on the one hand to the inductance in said anode cathode circuit and on the other hand to one of said parallel inductances in said aerial circuit.

2. A thermionic amplifier including a pair of thermionic tubes having anodes connected through a tank circuit including a tuned inductance, a connection between the midpoint of said inductance and the cathodes of said tubes, an antenna system including a capacity connected through parallel inductances to ground, a capacity in series with one of said inductances and a transmission line tapped at one end to the inductance in said output circuit and at the other'end to one of said parallel inductances.

3. In transmitting apparatus a thermionic generator, an aerial system, and means whereby the amplitude of the energy supplied to said aerial system may be varied without varying the frequency of the oscillations radiated including an aerial capacity connected through parallel inductances to ground, an inductance in the output circuit of said generator, and a transmission line tapped on the one hand to points on said last named inductance, and on the other hand to one of said parallel inductances.

4. In transmitting apparatus a thermionic generator, an aerial system, and means whereby the amplitude of the energy supplied to said aerial system may be varied without varying the frequency of the oscillations radiated including, an aerial capacity connected through parallel inductances to ground, a capacity in series with one of said parallel inductances, an inductance in the output circuit of said generator, and a transmission line tapped on the one hand to points on said last named inductance, and on the other hand to one of said parallel inductances.

5. Signalling means comprising a thermionic generator, an alternating current load circuit supplied by said generator, said load circuit including an inductance, and means whereby the amplitude of the energy supplied to said load circuit may be varied without varying the frequency of the oscillations impressed on said load circuit comprising a capacity and an inductance conductively connected in parallel to the inductance in said load circuit, an inductance in the output circuit of said generator, and a transmission line tapped on the one hand to said last named inductance and on the other hand to one of said parallel inductances.

6. Signalling means comprising a thermionic generator, an alternating current load circuit supplied by sai i generator, said load circuit including an inductance, and means whereby the amplitude of the energy supplied to said load circuit may be varied without varying the frequency of the oscillations impressed on said load circuit comprising an inductance conductively connected. in parallel to the inductance in said load circuit, an inductance in the output circuit of said generator, and a transmission line tapped on the one hand to points on said last named inductance and on the other hand tothe inductance in parallel with the load inductance.

FRED H. KROGER. 

